The drama centers on the romantic and comedic interactions between Shim Bo-nui, a woman who has blind faith in superstitions and fortune-tellings, with Je Soo-ho, CEO of a Game developer company who is a scientific and logical man.
A 26-year-old, attractive woman, who can learn quickly. On the other hand, she is blindly superstitious. She always follows the fortune-tellings of shaman Goo Shin, because she is told she was born unlucky. The shaman tells her that in order to save her sister Bo-ra, she has to sleep with a man born in the year of the Tiger. She meets Je Soo-ho and coincidentally he was born a Tiger.
A 31-year-old man. Born as a genius, he is a very logical and scientific person, who does not believe in anything supernatural. He is the owner and also CEO of a game developer company, Zeze Factory. He meets Bo-nui, who asks him to sleep with her.
A 24-year-old man. A Korean with Canadian citizenship. He is a famous professional tennis player, always placed high in ATP rankings. When he returns to South Korea, he immediately searches for his first love Bo-nui. He has a strained relationship with his father.
A 34-year-old woman. The director of a big sport company that represents Gun-wook. She is Soo-ho's first love. Ever since she lost her older brother in a fire accident, she never shows her true feelings to anyone, and always strives to be perfect in everyone's eyes.